Electronic devices continue to become smaller and more complex. As complexity increases, there is a tendency for these devices to require more buttons, including entire alphanumeric character sets, function-specific keys and ultimately cursor control. Combination keypad locks are more difficult to guess when an increased number combinations are possible.
Examples include: desktop and cellular telephonic products capable of accessing the Internet; two-directional hand held written communication devices; remote controls for television set top boxes offering computer functionality or interactive television; combination keypad lock interfaces and wired telephones with peripheral control abilities.
Such devices are problematic because the human hand remains relatively constant in size while the components shrink. The result is that the interface to the hand--the keypad--often dictates the smallest possible size of an electronic device. It is therefore increasingly important to minimize the size of the keypad without reducing the size of the keys to be smaller than the human hand may use comfortably.
Previous efforts to address this issue consist of the following:
Scale the Keypad Smaller
The most obvious way to increase the number of functions in a given area is to scale the keypad smaller, reducing key cap size and decreasing the distance between key cap centers. This technique causes the user to feel constrained. Products which use small keypads suffer from the impression that they are toy-like, largely because, in fact, they are scaled for use by a child. Decreasing key cap size makes the keys less comfortable to the full-sized adult finger. Decreasing the distance between key cap centers increases the likelihood of accidental input. Decreasing the size of the legend reduces legibility and the ease of viewing. In these ways, this solution is workable but far from optimal.
Chorded keyboards
Chorded keyboards have a relatively small number of keys, often linearly disposed to conform with the resting position of the human hand, which operate in combination to form each input, offering 2 raised to the N number of different inputs where N is the number of keys. The primary problem with this solution is that it requires the user to memorize 2 N input combinations and to develop the necessary motor skills. While this is a workable solution for extremely dedicated users, it is impractical and requires an unrealistically large amount of practice for most.
Modal Solutions
There are a variety of solutions in which individual keys are given a plurality of functions: Time variance modality varies the time between key operations to define the output function. This is non-intuitive and severely restricts the pace at which an operator may work; Function key modality alters the functionality of the keystroke(s) which follow in a predetermined manner. While this is an extremely common technique, it has limitations. While a function key doubles the possible outputs of a keypad, it also doubles the number of keystrokes required. Further, it is impractical to reduce the dimension of the standard 10-key keypad or the space required by the 26 letters of the alphabet by implementing a function key solution because the characters of these sets are of near-equal significance; Force sensitive modality incorporates a plurality of force-levels to a single button, and thereby a plurality of functions. Tests show that there is a wide variation in the forces naturally applied by users and wide variations in the levels of force sensitivity between users. The solution is highly non-intuitive. For these reasons, force sensitive keys are not widely applicable, nor desirable.
Smart Keys
There are a variety of solutions in which the character input by any given key is modified as a consequence of the previous letters entered, based on likely probabilities within a given language, such as that provided by Aiki Ltd, a Seattle company. With this technology, the probability of the device guessing correctly increases with the length of word. However, the first letter of each word in always a problem. Obviously any keyswitch technology, including the object of this invention, may be combined with a Smart key solution.
There are further goals beyond the primary objective of providing a tiny, easy-to-use keypad. Because the environment for miniaturized products is one of constant abuse, reliability and robustness are critical. Devices intended to survive within pockets and to be used at the dinner table must be water and crumb proof. Furthermore, the next generation of miniaturized devices will require a cursor control device that can be fully integrated, yet without compromising on overall robustness, manufacturability, or performance. With absolute miniaturization as the goal, even millimeters become significant for the entire product to fit into a pocket or onto a wrist.
What is desirable is a keypad which increases the number of functions which can be output from a given number of keys and within a defined area, without compromising the ergonomic advantages of full-size and individually operable key caps. It is further desirable to not require any learning or practice. The keypad would be non-modal to eliminate the confusion and errors commonly associated with modalities. Each output function would permanently correlate with a single key cap location. The identifying legends would be full-size for easy identification. Functions would be accessible by a single finger push. The keypad would be small without being toy-like because it is designed to accommodate a full-size human finger. Ideally a compact keypad would effect full-sized key caps with on center distances smaller than full-sized key cap dimensions allow. It would be low-cost yet robust, reliable and include a cursor control.
It is therefore a goal of the present invention to provide: a compact keypad in which each function may be actuated comfortably by an adult-sized human finger; an increased number of functions within a given area without compromising the ergonomic advantages of full-size key caps; a compact keypad in which each function may be accessed by a single finger motion; and an increased number of inputs without requiring memorization, training to use, or the introduction of a modality for normal operation.
It is yet further goal to provide a low cost, reliable, ruggedized miniature product that can withstand normal daily activities such as eating, drinking, and being tossed.
It is yet a further goal to decrease the accuracy required to reliably actuate adjacent keys of a keypad in which multiple adjacent keys are operated with a single push of a finger, especially for molded elastomeric sheets operating over printed circuit boards.
It is yet a further goal to reduce the force required to reliably actuate adjacent keys of a keypad in which multiple adjacent keys are operated with a single push of a finger, especially for molded elastomeric sheets operating over printed circuit boards.
It is yet a further goal to eliminate the electronic ambiguities inherent with simultaneous operation of the adjacent keys in a scan matrix.
It is yet still further a goal to provide a cursor control means that may be integrated within the constraints explained above.